Microtubules are known to play an important role in a variety of intracellular motile processes, including flagellar beating, axoplasmic transport, secretion, and mitosis. The best documented microtubule-related motile system is the flagellum, in which the dynein (ATPase) arms both bridge adjacent microtubules and serve as the motors for flagellar motility. The role of microtubules in axoplasmic transport and secretion is less well understood: electron microscopic studies show close associations between organelles and microtubules; drugs which disassemble microtubules either abolish or alter the organelle movements. Recent studies have shown that actomyosin might be involved in microtubule-related movements of granules during secretion. The ultrastructural arrangement of the actomyosin and microtubules, and the mechanisms by which the movements occur are unknown. The proposed research will: a) investigate the identity and localization of the components necessary for the secretion of insulin-containing beta-granules in pancreatic cells, b) fractionate the cells and isolate the microtubule-beta-granule complexes, and c) investigate the biochemical mechanims by which the microtubules participate in the directed organelle movements. Both high resolution light and electron microscopy will be used to assay the organelle movements and the components responsible for the movements. The in vitro associations of microtubules, associated proteins, and the beta-granules will be carried out on microscope slides and will be analyzed using dark field light microscopy.